The invention relates to an electromagnetically operable valve and a method for producing a magnet housing for a valve.
Conventional electromagnetically operable valves have an actuator that includes at least one solenoid coil, a magnet armature for opening and closing the valve and an outer conductive element, such as a magnet case, i.e., a magnet housing or conductive bracket, conducting the magnetic flux.
Usually such magnet housings are produced by surface machining. Lathing, milling, boring and fine-finishing steps are conventional methods for producing a magnet housing.
Furthermore, German Unexamined Patent Application No. 40 03 229 or U.S. Pat. No. 5,544,816 describe producing magnet housings for electromagnetically operable valves by deep drawing. In that case, the magnet housings they have a wide opening at one axial end to permit axial insertion of a solenoid coil. Additional covering elements are necessary in the region of the wide opening to close the magnetic circuit. To pass coil pins through, extra feed-through openings or cutouts must be provided in the magnet housing which are formed by boring or milling.
Another design possibility of an outer magnet housing is for two bracket-type conductive elements to partially surround the solenoid coil, as described in German Unexamined Patent Application No. 38 25 135. For example, these conductive elements are punched components brought into the desired form by shaping. Such conductive elements can also be executed as sintered brackets.
Independent of the magnet housings mentioned, German Unexamined Patent Application No. 39 04 448 to describes producing a magnet armature from a sheet-metal strip of slight thickness. The magnet armature, together with a sleeve-type connecting part and a spherical valve-closure member, is part of an axially moveable valve needle. A section is first punched out in the desired form from a sheet metal and is subsequently rolled or bent in such a way that a magnet armature is formed having a circular periphery.
The valve of the present invention has the advantage that it can be produced and mounted in a very simple manner. The magnet housing, at least partially surrounding the solenoid coil, is advantageously formed such that the solenoid coil can be inserted into it in the radial direction. The magnet housing is formed so that no additional components are necessary for closing the magnetic circuit around the solenoid coil. The magnet housing can be ideally mounted in the valve due to its shaping.
A further advantage is that reduced tolerance demands are made on the outside diameter of the core and valve-seat support, as well as the inside diameter of the magnet housing, without adversely influencing the magnetic junction between these components.
Additional advantageous further developments and improvements of the valve are possible.
The attachment areas are advantageously segmented, the segments being formed by a plurality of recesses in these attachment areas. The segments act like a collet and can be easily opened during mounting by a slight force action. Thus, the formation of a cutting and the development of scratches are avoided. Since the collet-like attachment areas are under prestress, the position of the magnet housing in the valve, e.g., on the core, is already well fixed in position after mounting.
The method of the present invention for producing a magnet housing for a valve has the advantage that a magnet housing can be produced in a simple manner which can largely surround a solenoid coil in the axial direction and in the circumferential direction without additional measures being necessary for closing the magnetic circuit. The magnet housing can already be formed using the method of the present invention in such a way that no further outer magnetic-circuit components are necessary, and no pass-through openings or cutouts have to be introduced using additional cutting-work methods such as milling or boring.